From nobody Tue Dec 16 20:02:19 2025 Received: from us-smtp-delivery-44.mimecast.com (us-smtp-delivery-44.mimecast.com [207.211.30.44]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 95BA317757 for ; Mon, 15 Jan 2024 15:48:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=kernel.org Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-107-_RghfqN5O6OKasyAw_gn3g-1; Mon, 15 Jan 2024 10:47:16 -0500 X-MC-Unique: _RghfqN5O6OKasyAw_gn3g-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id E73FE2825BBF; Mon, 15 Jan 2024 15:47:15 +0000 (UTC) Received: from localhost.redhat.com (unknown [10.45.226.182]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9B36F3C25; Mon, 15 Jan 2024 15:47:14 +0000 (UTC) From: Alexey Gladkov To: LKML , Linux Containers Cc: Andrew Morton , Christian Brauner , "Eric W . Biederman" , Joel Granados , Kees Cook , Luis Chamberlain , Manfred Spraul Subject: [RESEND PATCH v3 3/3] sysctl: Allow to change limits for posix messages queues Date: Mon, 15 Jan 2024 15:46:43 +0000 Message-ID: <6ad67f23d1459a4f4339f74aa73bac0ecf3995e1.1705333426.git.legion@kernel.org> In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 Content-Type: text/plain; charset="utf-8" All parameters of posix messages queues (queues_max/msg_max/msgsize_max) end up being limited by RLIMIT_MSGQUEUE. The code in mqueue_get_inode is where that limiting happens. The RLIMIT_MSGQUEUE is bound to the user namespace and is counted hierarchically. We can allow root in the user namespace to modify the posix messages queues parameters. Signed-off-by: Alexey Gladkov Link: https://lkml.kernel.org/r/7eb21211c8622e91d226e63416b1b93c079f60ee.16= 63756794.git.legion@kernel.org Signed-off-by: Eric W. Biederman --- ipc/mq_sysctl.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/ipc/mq_sysctl.c b/ipc/mq_sysctl.c index ebb5ed81c151..21fba3a6edaf 100644 --- a/ipc/mq_sysctl.c +++ b/ipc/mq_sysctl.c @@ -12,6 +12,7 @@ #include #include #include +#include =20 static int msg_max_limit_min =3D MIN_MSGMAX; static int msg_max_limit_max =3D HARD_MSGMAX; @@ -76,8 +77,43 @@ static int set_is_seen(struct ctl_table_set *set) return ¤t->nsproxy->ipc_ns->mq_set =3D=3D set; } =20 +static void mq_set_ownership(struct ctl_table_header *head, + struct ctl_table *table, + kuid_t *uid, kgid_t *gid) +{ + struct ipc_namespace *ns =3D + container_of(head->set, struct ipc_namespace, mq_set); + + kuid_t ns_root_uid =3D make_kuid(ns->user_ns, 0); + kgid_t ns_root_gid =3D make_kgid(ns->user_ns, 0); + + *uid =3D uid_valid(ns_root_uid) ? ns_root_uid : GLOBAL_ROOT_UID; + *gid =3D gid_valid(ns_root_gid) ? ns_root_gid : GLOBAL_ROOT_GID; +} + +static int mq_permissions(struct ctl_table_header *head, struct ctl_table = *table) +{ + int mode =3D table->mode; + kuid_t ns_root_uid; + kgid_t ns_root_gid; + + mq_set_ownership(head, table, &ns_root_uid, &ns_root_gid); + + if (uid_eq(current_euid(), ns_root_uid)) + mode >>=3D 6; + + else if (in_egroup_p(ns_root_gid)) + mode >>=3D 3; + + mode &=3D 7; + + return (mode << 6) | (mode << 3) | mode; +} + static struct ctl_table_root set_root =3D { .lookup =3D set_lookup, + .permissions =3D mq_permissions, + .set_ownership =3D mq_set_ownership, }; =20 bool setup_mq_sysctls(struct ipc_namespace *ns) --=20 2.43.0